Help with merlin prf unit

Discussion in 'Water Fed Pole Cleaning' started by Brooke, Sep 11, 2016.

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  1. Brooke

    Brooke Newcomer
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    Hi guys,
    I've recently bought and set up a merlin prf unit for home, now the incoming tds is around 350 and the water pressure is 50psi. The water produced is 20tds but I've read elsewhere from numerous forums that guys with similar set up getting much lower tds results. Is there something I can do to get better results or is this about right. Would buying a booster pump improve tds results
    Thanks in advance for any help
     
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  2. AGlassAct

    AGlassAct Active Member
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    That's pretty damn good Brooke for a Merlin tbh. If you stick a booster on it you will increase your productivity quite a bit and your TDS will drop slightly too. I've never fully tested my Merlin as I brought it when I first set up WFP as a cheap start up - I changed to a 4040 almost straight away as replacing the membranes wasn't much less than a HF4.


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  3. spruce

    spruce Grand Master
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    Alex has some good info on his site

    PRF RO - Reverse Osmosis Unit - Complete RO Systems - Water Treatment - Pure Water Systems - All Products Gardiner Pole Systems

    There is also a technical sheet in pdf format.

    93% rejection rate at 5.5 bar is a little better than the original Merlin, but not by much. I would do the waste to pure ratio test and see what you have. A fellow windie around the corner has an old Merlin and he fitted a gate valve onto his waste to throttle it back a bit more and gets much better rejection rates. We also have a water pressure of 50 psi.

    I would play around with this before buying a booster pump tbh. Then again, before buying a booster pump I would consider a 4040 with an HF5 membrane and put the money saved on a booster pump toward that.

    The old Merlins used to have an approx 5 waste to 1 pure production ratio when we tested his years ago.


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  4. Brooke

    Brooke Newcomer
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  5. Brooke

    Brooke Newcomer
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    Thanks for your replys, I actually got this from gardeners and tbh it's worked well for me, takes about 6hrs to fill up my 500l tank setting up was easy but had seen guys getting lower tds readings from same sort of set up as me and thought I could do more maybe to get same outcome via a booster pump.
     
  6. spruce

    spruce Grand Master
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    There's a poster on another forum who also bought one from Alex.

    24th April

    "Just finished installing my new R/O. It is a Pentair PRF-RO and is so easy-peasy that that even I can do it.

    It's about 345TDS in and 004 out and the inlet pressure gauge now reads 65-70 psi on 1/2" tubing in and 3/8" tubing out. I get about 70 litres an hour of pure which is more than adequate.

    The old RO-Man type (nominal 300gpd) started at about 009 out on 80 psi on 1/4" tubing and gave about 20 litres an hour of pure."


    An update as of Friday 13th May.

    "300 in and 008 out of the R/O and 60 litres per hour. So as suspected, not as good as it was between three and four weeks ago. I will be changing the filter 1st week in June so we shall see what difference that makes."

    I thought that 345 in and 4 out was just too good. That's 98.84% efficient.


    With 300 in and 8 out it is still 97.4% efficient so it still performing well by 4040 standards.

    But another poster on the same forum (not in the same area) isn't doing so well with his. His comments were that it was time to put his hands in his pockets for a 4040.

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  7. Brooke

    Brooke Newcomer
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    Thanks Spruce I appreciate you taking the time to post that I wasn't even aware of the 4040 before now so I'll look into it,is that what the majority of guys here are using here. What would be the difference between the merlin and the 4040?
     
  8. spruce

    spruce Grand Master
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    #8 spruce, Sep 13, 2016
    Last edited: Sep 13, 2016

    We have an update. The PRF is now producing water at 16ppm. It was worse as water through the r/o dropped. This cleaner has now fitted a 10" sediment prefilter before the r/o and replaced his sediment/carbon block combo. Its cheaper to replace this sediment filter than the carbon block in the r/o.

    4040 - here is an example second item down.

    Reverse Osmosis (RO) Systems and Water Filters with Axeon Membranes

    What is the difference between the two units? The predecessor to the PRF is the Merlin made by GE in the states.

    It was designed as an undercounter water purifier to be used in American kitchens. As such it does quite a good job. The pure outlet is connected to a separate tap in the kitchen sink. When the user opens the tap he get purified water. They even supply another prefilter to make the water taste nicer.

    So it doesn't matter if the water hasn't got all the calcium and magnesium removed by the r/o. 90% efficiency is OK for that application. Its recommended that the user replace filters every six to twelve months for residential applications.
    For most residential applications, the RO membrane elements should be replaced every two to four years. If the user expects to use more than 100 US gallons of water a day then GE recommended that a separate chlorine prefilter be added. This indicates to me that they would expect the unit not to work much.

    Then window cleaners come along wanting huge amounts of water processed daily in comparison and because the Merlin is so user friendly it gets asked to provide this service. So easy to install, just fit a ballcock valve to an IBC tank and once the tank is full the pure is stopped which switches the r/o off.

    As window cleaners we want pure water, or as pure as we can get. The less efficient an r/o is, the more resin is going to cost to remove the balance of those impurities. So whilst a cleaner would initially save money on his r/o purchase, it could cost him more over the course of the lifetime of the r/o.

    Lets use my mate with his Merlin around the corner as an example. Our 4040 was supplying 2 full time cleaners and a part time cleaner. He was supplying himself and another cleaner who was just doing tops wfp.
    I would estimate that we were using more water over a year than he was. We used a 1/4 of a bag of resin in the first year I had my 4040 compared to a full bag he used.
    I know this because he asked me for some to fill his di as he had forgotten to reorder a new bag. So his Merlin cost him £60 more than mine in resin in the first year.

    Gardiners has the PRF for £322 + VAT. Daqua has a 4040 for 445.00 + VAT. So the difference in price will be made up in resin costs in 2 years.

    OK. Gardiner's say that the r/o produces 2600 liters a day (24 hour day) in ideal testing conditions. The 4040 does 9450 liters per 24 hour day, also in ideal testing conditions - that's 3.5 times the amount of water in an hour.

    For me, my 4040 has a HF5 membrane and works with water pressure at 50 psi. My waste to pure ratio is 1 to 1. My membranes are 4 years old, water in 100 to 120, water out 2. Product (pure) water = 2lpm which is more than enough for us. Yes we have had an additional cost of fitting a float switch in the tank that cuts water to the r/o when the IBC tank is full, but having sufficient water to supply the 3 of us without rationing was brilliant.

    I'm not saying that you should replace your r/o unit with a more efficient one. You have it now so I would keep it, just expecting to pay a little more over the course of its life time in resin.

    Replacing 2 PRF membranes is much cheaper than a 4040, so in 4 years time (or whenever you need to replace them) your PRF will start saving you some money. The jury is out on the fiberdyne carbon block prefilter. Its good for 38,000 liters (waste and pure) but if you have sediment laden water like we experience, then I suggest you put a 10" single housing sediment prefilter inline before r/o to save the fiberdyne filter which is much more expensive.

    I would also suggest you fit a separate water meter on the line into you r/o so you know when the replace the fiberdyne filter (the first one.) Chlorine destroys membranes so its a necessity that the fiberdyne carbon block is replaced timeously after 38000 liters.


    https://www.uswatersystems.com/pdf/Merlin-Manual.pdf

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  9. Brooke

    Brooke Newcomer
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    Brilliant thanks so much for that very interesting indeed definitely given me food for thought
     
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